Bug #67978 [Opn->Nab]: Bug with floating number

Edit report at https://bugs.php.net/bug.php?id=67978&edit=1 ID: 67978 Updated by: requinix@php.net Reported by: tripollite at gmail dot com Summary: Bug with floating number -Status: Open +Status: Not a bug Type: Bug Package: *Math Functions Operating System: Debian 7 PHP Version: Irrelevant Block user comment: N Private report: N New Comment: Floating point values have a limited precision. Hence a value might not have the same string representation after any processing. That also includes writing a floating point value in your script and directly printing it without any mathematical operations. If you would like to know more about "floats" and what IEEE 754 is, read this: http://www.floating-point-gui.de/ Thank you for your interest in PHP. If you need numbers rounded to a certain precision then you need to do that yourself. Previous Comments: ------------------------------------------------------------------------ [2014-09-08 12:47:16] tripollite at gmail dot com Description: ------------ Var dump fail to show right number but this number is used in memory to make calcul. it should respect precision by cutting floating numbers or showing the right number Test script: --------------- http://3v4l.org/AFQF6 <?php $b = 0.27*28; $a = round($b,2); var_dump($a-$b); $b = 0.270000000000001; $a = round($b,2); var_dump($b);var_dump($a-$b); Expected result: ---------------- float(0) float(0.27) float(0) Actual result: -------------- float(-8.8817841970013E-16) float(0.27) float(-9.9920072216264E-16) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=67978&edit=1